U.S. patent application number 14/322324 was filed with the patent office on 2014-10-23 for communication method, communication terminal, and base station apparatus.
The applicant listed for this patent is FUJITSU LIMITED. Invention is credited to Hitoshi Yokoyama.
Application Number | 20140315577 14/322324 |
Document ID | / |
Family ID | 48873076 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140315577 |
Kind Code |
A1 |
Yokoyama; Hitoshi |
October 23, 2014 |
COMMUNICATION METHOD, COMMUNICATION TERMINAL, AND BASE STATION
APPARATUS
Abstract
A communication method is provided. The communication method
includes specifying, by a communication apparatus, a position of a
coverage hole which is a region where a terminal does not receive a
radio wave with an intensity which allows communication to be
performed, the communication apparatus being included in a wired
network in which the terminal performs communication via a base
station. The communication method also includes determining, by the
communication apparatus, a hole proximity terminal which has a
possibility of coming close to the coverage hole. The communication
method also includes transmitting, by the communication apparatus,
to the hole proximity terminal a notification message for notifying
of hole information to specify a position of the coverage hole.
Inventors: |
Yokoyama; Hitoshi;
(Shinagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJITSU LIMITED |
Kawasaki-shi |
|
JP |
|
|
Family ID: |
48873076 |
Appl. No.: |
14/322324 |
Filed: |
July 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2012/051702 |
Jan 26, 2012 |
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14322324 |
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Current U.S.
Class: |
455/456.1 |
Current CPC
Class: |
H04W 24/04 20130101;
H04W 24/10 20130101; H04W 4/02 20130101; H04W 4/029 20180201 |
Class at
Publication: |
455/456.1 |
International
Class: |
H04W 16/24 20060101
H04W016/24; H04W 4/02 20060101 H04W004/02 |
Claims
1. A communication method comprising: specifying, by a
communication apparatus, a position of a coverage hole which is a
region where a terminal does not receive a radio wave with an
intensity which allows communication to be performed, the
communication apparatus being included in a wired network in which
the terminal performs communication via a base station;
determining, by the communication apparatus, a hole proximity
terminal which has a possibility of coming close to the coverage
hole; and transmitting, by the communication apparatus, to the hole
proximity terminal a notification message for notifying of hole
information to specify a position of the coverage hole.
2. The communication method according to claim 1, receiving, by the
communication apparatus, a suspended position notification for
notifying a position where communication with the base station is
suspended from a terminal which restarts communication after the
communication with the base station is suspended due to a weak
intensity of a radio wave received from the base station; setting,
by the communication apparatus, a position specified by the
suspended position notification as the position of the coverage
hole; transmitting, by the communication apparatus, a control
message for controlling a parameter used in the base station for
reducing the coverage hole, and transmitting, by the communication
apparatus, the notification message to the hole proximity terminal
when the coverage hole is not reduced by controlling the parameter
in the base station.
3. The communication method according to claim 1, wherein the
notification message includes a position of the coverage hole and a
warning area threshold value, and wherein the hole proximity
terminal displays an indication for giving a warning of being
located around a region where communication is not performed to a
user of the hole proximity terminal on a display provided in the
hole proximity terminal, when a distance from the position of the
coverage hole to the hole proximity terminal is equal to or smaller
than the warning area threshold value.
4. The communication method according to claim 1, wherein the wired
network includes a positional information server which holds a
position of a terminal which communicates with the wired network,
wherein the communication apparatus notifies the positional
information server of an observation area threshold value for
determining an observation area which is a target for observing a
distance from the coverage hole, and inquires the positional
information server about a terminal whose distance from the
coverage hole is equal to or smaller than the observation area
threshold value, and wherein the communication apparatus sets a
terminal notified from the positional information server as the
hole proximity terminal.
5. The method according to claim 1, wherein the wired network
includes a control apparatus which manages a movement of a
terminal, wherein the communication apparatus notifies the control
apparatus of a position of the coverage hole when the coverage hole
is located in a communication area of the control apparatus, and
wherein the control apparatus transmits the notification message to
a terminal located in the communication area as the hole proximity
terminal via a connected base station.
6. The method according to claim 1, wherein the wired network
includes the base station, wherein the communication apparatus
notifies the base station of a position of the coverage hole when
the coverage hole is located in a communication area of the base
station, and wherein the base station transmits the notification
message to a terminal located in the communication area as the hole
proximity terminal.
7. The communication method according to claim 4, wherein the
notification message includes a position of the coverage hole and
an observation area threshold value which is greater than a warning
area threshold value, and wherein the hole proximity terminal
decreases a frequency of obtaining a distance from the position of
the coverage hole to the hole proximity terminal when the distance
from the position of the coverage hole to the hole proximity
terminal exceeds the observation area threshold value.
8. A communication terminal comprising: a reception unit configured
to receive hole information indicating a position of a coverage
hole which is a region where a terminal does not receive a radio
wave with an intensity which allows communication to be performed,
and notification information for notifying a warning area threshold
value; and a processor configured to calculate a distance from a
present location to a position of the coverage hole when the
notification information is received and to perform a process for
giving a warning of being located around a region where
communication is not performed to a user of the hole proximity
notification, when a distance calculated by the processor is equal
to or smaller than the warning area threshold value.
9. The communication terminal according to claim 8, wherein the
notification information further includes an observation area
threshold value which is greater than the warning area threshold
value, and wherein, when the distance calculated by the processor
exceeds the observation area threshold value, the processor
decreases a frequency of calculating a distance from a present
location of the communication terminal to the coverage hole until
the reception unit receives the notification information again.
10. A base station apparatus which performs wireless communication
with a terminal and also performs communication with a
communication apparatus connected thereto via a wired network, the
base station apparatus comprising: a reception unit configured to
receive information for specifying a position of a coverage hole
which is a region where the terminal does not receive a radio wave
with an intensity which allows communication to be performed, from
the communication apparatus; a processor configured to specify a
terminal connected to the base station apparatus, a terminal which
requests new connection to the base station apparatus, and a
terminal which is handed over to the base station, to generate a
notification message for notifying hole information to specify a
position of the coverage hole; and a transmission unit configured
to transmit the notification message to a terminal specified by the
processor.
11. The base station apparatus according to claim 10, wherein, when
a transmission destination of the notification message is a
terminal which is handed over to the base station apparatus, the
processor includes a position of the coverage hole in a signaling
message for responding to a handover request, and wherein, when a
transmission destination of the notification message is a terminal
which requests new connection to the base station apparatus, the
processor includes a position of the coverage hole in a signaling
message for responding to a connection request.
12. A control apparatus which manages a movement of a terminal,
comprising: a reception unit configured to receive information for
specifying a position of a coverage hole which is a region where
the terminal does not receive a radio wave with an intensity which
allows communication to be performed, from a communication
apparatus which is connected thereto via a wired network; a
processor configured to specify a terminal connected to the control
apparatus, a terminal which sends a request for initial attachment
to the control apparatus, and a terminal which updates a tracking
area of the control apparatus; to generate a notification message
for notifying hole information to specify a position of the
coverage hole; and a transmission unit configured to transmit the
notification message to a terminal specified by the processor.
13. The control apparatus according to claim 12, wherein the
processor includes, in the notification message, a position of the
coverage hole, and a warning area threshold value which is a
distance between a terminal and the coverage hole at the time of
starting a process for giving a warning that the terminal is
located around the coverage hole to a user of the terminal which is
a transmission destination of the notification message.
14. A server apparatus which provides an application, comprising: a
reception unit configured to receive information for specifying a
position of a coverage hole which is a region where a terminal does
not receive a radio wave with an intensity which allows
communication to be performed, from a communication apparatus which
is connected thereto via a wired network; a memory configured to
record information for identifying a terminal which is provided
with the application; a processor configure to generate a
notification message for notifying hole information to specify a
position of the coverage hole; and a transmission unit configured
to transmit the notification message to a terminal which is
recorded in the terminal information database.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT application of
International Application PCT/JP2012/051702 filed on Jan. 26, 2012,
and designated the U.S., the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The present invention relates to communication which is
performed by a communication terminal via a base station
apparatus.
BACKGROUND
[0003] When a mobile phone system is changed, or a system which has
been destroyed due to natural disasters is recovered, a new base
station is installed. In this case, a coverage hole may occur which
is a region where a mobile phone and the base station cannot
communicate with each other until installation of the base station
is completed. Therefore, minimization of drive test (MDT) is
currently being developed in order to remove a coverage hole. In a
system using the MDT, a coverage hole is specified, and an
adjustment or the like of an antenna is performed in order to
remove the specified coverage hole.
[0004] As a technique related to detection of a region where it is
hard to perform communication, a system has been designed which can
distinguish a radio link failure location at the time of handover.
In this system, in a case where line disconnection occurs in a
first cell, and a mobile terminal is connected to a second cell
again within a predefined time from the time when the line
disconnection occurs, or within a movement distance, the mobile
terminal reports at least one of information on the first cell and
information on the second cell to a base station.
DOCUMENTS OF RELATED ARTS
Patent Documents
[0005] [Patent Document 1] International Publication Pamphlet No.
WO 2009/060935
SUMMARY
[0006] According to an aspect of the embodiments, a communication
method is provided. The communication method includes specifying,
by a communication apparatus, a position of a coverage hole which
is a region where a terminal does not receive a radio wave with an
intensity which allows communication to be performed, the
communication apparatus being included in a wired network in which
the terminal performs communication via a base station. The
communication method also includes determining, by the
communication apparatus, a hole proximity terminal which has a
possibility of coming close to the coverage hole. The communication
method also includes transmitting, by the communication apparatus,
to the hole proximity terminal a notification message for notifying
of hole information to specify a position of the coverage hole.
[0007] The object and advantages of the invention will be realized
and attained by means of the elements and combinations particularly
pointed out in the claims.
[0008] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a diagram illustrating an example of a
communication method according to an embodiment.
[0010] FIG. 2 is a diagram illustrating configuration examples of
apparatuses which operate in a first embodiment.
[0011] FIG. 3 is a diagram illustrating an example of a hole
information database.
[0012] FIG. 4 is a diagram illustrating an example of a positional
information database.
[0013] FIG. 5 is a diagram illustrating hardware configuration
examples of the apparatuses.
[0014] FIG. 6 is a diagram illustrating an example of a positional
relationship between a coverage hole and terminal apparatuses.
[0015] FIG. 7 is a diagram illustrating an example of a message
format.
[0016] FIG. 8 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole
cannot be improved.
[0017] FIG. 9 is a diagram illustrating examples of a calculation
result in a calculation unit and a determination result of whether
or not a warning is issued.
[0018] FIG. 10 is a flowchart illustrating an example of an
operation of a terminal apparatus which has received a hole
notification.
[0019] FIG. 11 is a diagram illustrating a configuration example of
apparatuses which operate in a second embodiment.
[0020] FIG. 12 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole
cannot be improved in the second embodiment.
[0021] FIG. 13 is a diagram illustrating an example of a message
format.
[0022] FIG. 14 is a flowchart illustrating an example of a process
in a base station when a notification of a position of a coverage
hole has been sent.
[0023] FIG. 15 is a flowchart illustrating an example of an
operation of a terminal apparatus which has been notified of a
position of a coverage hole.
[0024] FIG. 16 is a diagram illustrating a configuration example of
apparatuses which operate in a third embodiment.
[0025] FIG. 17 is a diagram illustrating an example of a message
format.
[0026] FIG. 18 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole
cannot be reduced in the third embodiment.
[0027] FIG. 19 is a flowchart illustrating an example of a process
in an MME when a notification of a position of a coverage hole has
been sent.
[0028] FIGS. 20A and 20B are flowcharts illustrating an example of
an operation of a terminal apparatus which has been notified of a
position of a coverage hole.
[0029] FIG. 21 is a diagram illustrating an example of a system
according to a fourth embodiment.
[0030] FIG. 22 is a diagram illustrating a configuration example of
an application server.
[0031] FIG. 23 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole
cannot be reduced in the fourth embodiment.
[0032] FIG. 24 is a diagram illustrating an example of a
notification message format.
[0033] FIG. 25 is a flowchart illustrating an example of an
operation of a terminal apparatus which has been notified of a
position of a coverage hole.
DESCRIPTION OF EMBODIMENTS
[0034] FIG. 1 illustrates an example of a communication method
according to an embodiment. FIG. 1 illustrates an example of a long
term evolution (LTE) network. It is assumed that terminal
apparatuses 10a and 10b communicate with an apparatus which is a
communication destination via a base station 20. The base station
20 is connected to a wired network, and the wired network includes
mobility management equipment (MME) 30, an element manager (EM) 40,
an MDT management server 50, and a positional information server
80.
[0035] It is assumed that the terminal apparatus 10a is a terminal
of a user A, and the terminal apparatus 10b is a terminal of a user
B. It is assumed that a position of the terminal apparatus 10a is
changed according to a movement of the user A, and a position of
the terminal apparatus 10b is changed according to a movement of
the user B. It is assumed that each terminal apparatus 10 notifies
the positional information server 80 of the present position, and
the positional information server 80 holds positional information
of the terminal apparatus 10 in correlation with an identifier of
the terminal apparatus 10. In addition, in this example, it is
assumed that the user A moves in and around a coverage hole 1 or
through the coverage hole 1, and thus the terminal apparatus 10a
enters the coverage hole 1 multiple times.
[0036] First, the terminal apparatus 10a is assumed to cross the
coverage hole 1 according to a movement of the user A. The terminal
apparatus 10a cannot communicate with the base station 20 if the
terminal apparatus enters the coverage hole 1, but restarts
communication with the base station 20 if the terminal apparatus
leaves the coverage hole 1. In addition, the terminal apparatus 10a
transmits a notification including information for specifying a
position where communication is suspended, to the MDT management
server 50. In the following description, the notification including
information for specifying a position where communication is
suspended is referred to as a radio link failure (RLF) notification
in some cases. Here, the RLF notification indicates a position
where communication between the terminal apparatus 10 and the base
station 20 is suspended, and thus can be said to be information
indicating a position of the coverage hole 1. The RLF notification
is received by the MDT management server 50 via the base station 20
and the EM 40.
[0037] The MDT management server 50 specifies a position of the
coverage hole 1 from the information included in the RLF
notification, and calculates a parameter which is used for setting
of an antenna of the base station 20 in order to reduce the
coverage hole 1. The MDT management server 50 notifies the base
station 20 of the calculated parameter. The base station 20 adjusts
the antenna by using the parameter of which a notification has been
sent from the MDT management server 50.
[0038] At this time, it is assumed that, although the antenna is
adjusted, the coverage hole 1 is not removed, and the terminal
apparatus 10a enters the coverage hole 1 again. Then, as described
above, the terminal apparatus 10a transmits the RLF notification to
the MDT management server 50 via the base station 20 when
communication with the base station 20 is restarted.
[0039] If the RLF notification for the coverage hole 1 for which
the parameter in the base station 20 has been changed is received
again, the MDT management server 50 determines that the coverage
hole 1 cannot be reduced. In addition, it is assumed that the
number of times of changing parameters in the base station 20
before determining whether or not the coverage hole 1 can be
reduced is arbitrary in accordance with implementations
[0040] If the MDT management server 50 detects the coverage hole 1
which cannot be reduced, the MDT management server 50 notifies the
terminal apparatus 10 located around the coverage hole 1 of the
position of the coverage hole 1. At this time, the MDT management
server 50 inquires the positional information server 80 about the
terminal apparatus 10 located around the coverage hole 1. The
positional information server 80 determines that the terminal
apparatus 10 whose distance from the coverage hole 1 is smaller
than a first threshold value is located around the coverage hole 1.
Here, it is assumed that the MDT management server 50 is notified
of the terminal apparatus 10a and the terminal apparatus 10b as
terminal apparatuses located around the coverage hole 1. In the
following description, a terminal apparatus located around the
coverage hole 1 is referred to as a "hole proximity terminal" in
some cases. The MDT management server 50 notifies the terminal
apparatus 10a and the terminal apparatus 10b of the position of the
coverage hole 1.
[0041] When a notification of the position of the coverage hole 1
is sent from the MDT management server 50, the terminal apparatus
10b stores the position of the coverage hole 1, and periodically
obtains a distance between a position of the terminal apparatus 10b
and the position of the coverage hole 1. If a distance between the
terminal apparatus 10b and the coverage hole 1 becomes equal to or
smaller than a second threshold value, the terminal apparatus 10b
outputs warning information in a method in which the user B can
recognize the warning information. For example, the terminal
apparatus 10b may display information for notifying of being close
to the coverage hole 1 on a display. The terminal apparatus 10a is
also operated in the same manner as the terminal apparatus 10b.
[0042] In addition, a notification of a position of the coverage
hole 1 may be performed by the base station or the MME 30. In this
case, the base station may notify the terminal apparatus 10
connected to the base station of a position of the coverage hole 1.
Likewise, the MME 30 may notify the terminal apparatus 10 connected
to the MME 30 of a position of the coverage hole 1.
[0043] As mentioned above, if the method according to the
embodiment is employed, since a warning is issued to a user of the
terminal apparatus 10 when the terminal apparatus 10 comes close to
the coverage hole 1 which is determined as being incapable of being
improved, the user easily avoid the coverage hole so that
communication can be performed.
First Embodiment
[0044] In the following description, for better differentiation
between the first threshold value and the second threshold value,
the first threshold value is referred to as an "observation area
threshold value" and the second threshold value is referred to as a
"warning area threshold value" in some cases. The threshold values
are assumed to be stored in the MDT management server 50 in
advance.
[0045] [Apparatus Configuration]
[0046] FIG. 2 illustrates configuration examples of apparatuses
which operate in the first embodiment. The terminal apparatus 10
includes a wireless unit 13, an RLF generation unit 14, a
calculation unit 15, a warning unit 16, a position detection unit
17, and a positional information generation unit 18. In addition,
the wireless unit 13 includes a wireless transmission unit 11, and
a wireless reception unit 12. The wireless transmission unit 11 and
the wireless reception unit 12 perform wireless communication with
the base station 20. The RLF generation unit 14 generates an RLF
notification including a position where communication between the
terminal apparatus 10 and the base station 20 fails and an
identifier for identifying the base station 20 which has performed
the communication before the communication is suspended. The RLF
notification generated by the RLF generation unit 14 is transmitted
from the wireless transmission unit 11 toward the base station 20,
and is transmitted from the base station 20 to the MDT management
server 50.
[0047] If the terminal apparatus 10 is notified of a position of
the coverage hole 1, the calculation unit 15 stores information
thereon. In addition, the calculation unit 15 calculates a distance
between the coverage hole 1 and the terminal apparatus 10, and
outputs a calculation result to the warning unit 16. The warning
unit 16 holds the warning area threshold value (second threshold
value) of which the terminal apparatus 10 has been notified. The
warning unit 16 issues a warning in a method in which a user of the
terminal apparatus 10 can recognize the warning if a value
calculated by the calculation unit 15 is equal to or smaller than
the warning area threshold value, so as to attract the user's
attention. For example, the warning unit 16 may generate an alarm
sound from a speaker (not illustrated) provided in the terminal
apparatus 10. Further, a position of the coverage hole 1 whose
distance from the terminal apparatus 10 is equal to or smaller than
the warning area threshold value and the present position of the
terminal apparatus 10 may be displayed on a display (a display 101
of FIG. 5) of the terminal apparatus 10.
[0048] The position detection unit 17 detects the present location
of the terminal apparatus 10. For example, the position detection
unit 17 may detect a position of the terminal apparatus 10 by using
a GPS. In addition, the position detection unit 17 may acquire
positional information by using an assisted global navigation
satellite system (A-SMSS) or observed time difference of arrival
(OTDOA). The position detection unit 17 outputs information for
specifying the detected position to the calculation unit 15 and the
positional information generation unit 18. The positional
information generation unit 18 generates a notification (positional
information notification) including the information acquired from
the position detection unit 17. The positional information
generation unit 18 transmits the positional information
notification to the positional information server 80 via the
wireless transmission unit 11.
[0049] The base station 20 includes a wireless unit 23, a parameter
acquisition unit 24, a tilt angle adjustment unit 25, an interface
28, and an antenna 29. A communication area of the base station 20
is formed by radio waves from the antenna 29. The wireless unit 23
includes a wireless transmission unit 21 and a wireless reception
unit 22, and performs wireless communication with the terminal
apparatus 10 located within the communication area of the base
station 20. The interface 28 is provided with a transmission unit
26 and a reception unit 27. The interface 28 performs communication
with the MME 30, the EM 40, the MDT management server 50, the
positional information server 80, and the like via links. When a
message including a parameter used to adjust the antenna 29 is
received from the MDT management server 50, the parameter
acquisition unit 24 extracts the parameter therefrom. The parameter
acquisition unit 24 outputs the obtained parameter to the tilt
angle adjustment unit 25. The tilt angle adjustment unit 25 adjusts
a tilt angle of the antenna 29. The tilt angle adjustment unit 25
may use the parameter which is input from the parameter acquisition
unit 24, when a tilt angle is adjusted.
[0050] The MME 30 is connected to one or more base stations 20. The
MME 30 is a control apparatus which controls the connected base
station 20. The MME 30 is assumed to store an identifier of the
connected base station 20.
[0051] The EM 40 includes an interface 43 and a packet processing
unit 44. The interface 43 is provided with a transmission unit 41
and a reception unit 42, and performs communication with the MME
30, the MDT management server 50, the base station 20, and the
like. The EM 40 stores connection states (network information) of
the base station 20, the MME 30, the MDT management server 50, and
the positional information server 80. The packet processing unit 44
performs a transfer process of packets which are received from the
MDT management server 50, the MME 30, and the base station 20, on
the basis of the stored network information. In addition, the EM 40
sends a notification of the network information in response to an
inquiry from the MDT management server 50. Further, the packet
processing unit 44 processes a packet as appropriate which is sent
to the EM 40.
[0052] The MDT management server 50 includes an interface 53, a
hole information database 54, a hole control unit 60, and a
notification unit 70. The hole control unit 60 includes an RLF
processing unit 61, a parameter changing unit 62, and a hole
determination unit 63. The notification unit 70 includes a terminal
determination unit 71 and a message generation unit 72. The
interface 53 is provided with a transmission unit 51 and a
reception unit 52, and performs communication with the base station
20, the MME 30, and the positional information server 80 via
links.
[0053] The RLF processing unit 61 acquires an RLF notification
which is transmitted from the terminal apparatus 10, via the base
station 20 and the reception unit 52. The RLF processing unit 61
grasps a position where communication between the terminal
apparatus 10 and the base station 20 is suspended, from the RLF
notification. The RLF processing unit 61 records the position whose
notification has been sent by using the RLF notification, in the
hole information database 54 as a position where the coverage hole
1 is present. In addition, the RLF processing unit 61 may count the
number of notifications for each position whose notification has
been sent by using the RLF notification, and may register the
position whose notification has been sent by using the RLF
notification in the hole information database 54 when the number of
notifications is equal to or larger than a threshold value.
[0054] FIG. 3 illustrates an example of the hole information
database 54. The hole information database 54 records a position of
the coverage hole 1, an identifier for identifying the base station
20 of which communication with the terminal apparatus 10 is
suspended, and a possibility that the coverage hole 1 can be
reduced. The position of the coverage hole 1 is information for
specifying latitude, longitude, and a height from the earth's
surface of the coverage hole 1.
[0055] The coverage hole 1 may possibly be reduced or removed
through an adjustment of setting of the antenna 29 of the base
station 20 which includes the coverage hole 1 in a communication
area thereof. In addition, the coverage hole 1 may also possibly be
reduced or removed by adjusting the antenna 29 of the base station
20 of which the communication area is adjacent to the coverage hole
1. The base station 20 whose communication with the terminal
apparatus 10 is suspended includes the coverage hole 1 in a
communication area thereof or has a communication area adjacent to
the coverage hole 1. Therefore, the RLF processing unit 61 records
an identifier of the base station 20 whose notification has been
sent by using an RLF notification in the hole information database
54 in correlation with the coverage hole 1. In addition, the RLF
processing unit 61 sets a reduction possibility of a newly
registered coverage hole 1 to "Yes".
[0056] The parameter changing unit 62 determines a parameter for
changing setting of the antenna 29 of a base station which is
correlated with a position of the coverage hole 1. Next, the
parameter changing unit 62 generates a message for notifying the
determined parameter, and transmits the message to the base station
20 via the transmission unit 51. Hereinafter, the parameter for
changing setting of the antenna 29 is referred to as a "changing
parameter" in some cases. In addition, the parameter changing unit
62 notifies the hole determination unit 63 that the message for
notifying the changing parameter has been transmitted.
[0057] The hole determination unit 63 counts the number of times
the message including the changing parameter is transmitted to the
base station 20 whose communication area includes the coverage hole
1 or the base station 20 whose communication area is adjacent to
the coverage hole 1 for each coverage hole 1. If another RLF
notification is received in relation to the coverage hole 1 for
which the number of times of transmission of a message including
the changing parameter exceeds a threshold value, the hole
determination unit 63 determines that the coverage hole 1 cannot be
reduced. The hole determination unit 63 sets a reduction
possibility of the hole information database 54 to "No" in relation
to the coverage hole 1 which is determined as being incapable of
being reduced. The hole determination unit 63 notifies the terminal
determination unit 71 of the coverage hole 1 which has no reduction
possibility.
[0058] The terminal determination unit 71 inquires the positional
information server 80 about the terminal apparatus 10 whose
distance from the coverage hole 1 which is determined as there
being no reduction possibility is equal to or smaller than the
observation area threshold value (first threshold value). The
terminal determination unit 71 outputs an identifier of the
terminal apparatus 10 whose notification has been sent from the
positional information server 80, to the message generation unit 72
in correlation with the coverage hole 1. The message generation
unit 72 generates a notification message for notifying a position
of the coverage hole 1, setting a destination to each terminal
apparatus 10 which has been input from the terminal determination
unit 71. The message generation unit 72 transmits the generated
notification message to the destination via the transmission unit
51.
[0059] The positional information server 80 includes an interface
83, a positional information database 84, a terminal retrieval unit
85, and a positional information update unit 86. The interface 83
is provided with a transmission unit 81 and a reception unit 82,
and performs communication with the MDT management server 50 and
the like. When a positional information notification is received
from the terminal apparatus 10, the positional information update
unit 86 records a position of each terminal apparatus 10 in the
positional information database 84 in correlation with an
identifier of the terminal apparatus 10. FIG. 4 illustrates an
example of the positional information database 84. The terminal
retrieval unit 85 retrieves an identifier of the terminal apparatus
10 whose distance from the coverage hole 1 whose notification has
been sent from the MDT management server 50 is equal to or smaller
than the observation area threshold value, in response to an
inquiry from the MDT management server 50. At this time, the
terminal retrieval unit 85 uses the positional information database
84 as appropriate, and transmits a retrieval result to the MDT
management server 50. When positional information is received from
the terminal apparatus 10, the positional information update unit
86 updates the positional information database 84.
[0060] FIG. 5 is a diagram illustrating hardware configuration
examples of the apparatuses. The terminal apparatus 10 includes the
display 101, a central processing unit (CPU) 102, a hard disk drive
(HDD) 103, a memory 104, a digital signal processor (DSP) 105, and
a wireless radio frequency (RF) circuit 106. The wireless unit 13
is realized by the wireless RF circuit 106 and the DSP 105. The RLF
generation unit 14, the calculation unit 15, the warning unit 16,
the position detection unit 17, and the positional information
generation unit 18 are realized by the CPU 102. In this case, the
CPU 102 reads and executes a program recorded on the HDD 103 as
appropriate.
[0061] The base station 20 includes a wireless RF circuit 111, a
DSP 112, a CPU 113, a memory 114, and an interface 115. The
wireless unit 23 is realized by the wireless RF circuit 111 and the
DSP 112. The parameter acquisition unit 24 and the tilt angle
adjustment unit 25 are realized by the CPU 113. The interface 28 is
realized by the interface 115.
[0062] The MME 30 includes a CPU 121, an HDD 122, and an interface
123. The EM 40 includes a CPU 131, an HDD 132, and an interface
133, and the interface 43 is realized by the interface 133. In
addition, the packet processing unit 44 is realized by the CPU 131.
The MDT management server 50 includes a CPU 141, an HDD 142, and an
interface 143. The interface 53 is realized by the interface 143.
The hole control unit 60 and the notification unit 70 are realized
by the CPU 141. The HDD 142 stores the hole information database
54, and also stores data used for an operation of the hole control
unit 60 or the notification unit 70 as appropriate. The positional
information server 80 includes a CPU 151, an HDD 152, and an
interface 153. The interface 83 is realized by the interface 153.
The terminal retrieval unit 85 and the positional information
update unit 86 are realized by the CPU 151. The HDD 152 stores the
positional information database 84, and also stores data used for
an operation of the terminal retrieval unit 85 or the positional
information update unit 86 as appropriate.
[0063] [Communication Method]
[0064] FIG. 6 illustrates examples of a positional relationship
between a coverage hole 1a and terminal apparatuses MS1 to MS5.
Hereinafter, a description will be made of an example of a case
where the coverage hole 1a is specified by information whose
notification is sent from the terminal apparatuses MS1 to MS3, and
a notification message is transmitted to the terminal apparatuses
MS1 to MS4 whose distances from the coverage hole 1a are equal to
or smaller than the observation area threshold value. In addition,
MS1 to MS5 are assumed to be identifiers (terminal IDs) of the
terminal apparatuses 10. Further, the coverage hole 1a is assumed
to be located in a communication area of abase station BS1.
[0065] (1) It is assumed that the respective terminal apparatuses
MS1 to MS5 are distributed as illustrated in a state 201. Each of
the terminal apparatuses MS1 to MS5 periodically transmits a
positional information notification to the positional information
server 80. FIG. 7 illustrates an example of a format of a
positional information notification 301. The positional information
notification 301 includes a header, a message type field, a
terminal ID field, a terminal position field, a time stamp, a
movement speed field, and a measurement method field. The
positional information server 80 is recorded as a destination in
the header. A value indicating the positional information
notification is set in the message type field. Here, it is assumed
that a type field=0 indicates the positional information
notification. A position of a terminal apparatus is recorded as
information on latitude, longitude, and a height of a terminal
apparatus in the terminal position field. The time when the
position recorded in the terminal position field is measured as the
present location is recorded in the time stamp field, and a
movement speed of the terminal apparatus 10 is recorded in the
movement speed field. A measurement method used to acquire
positional information is recorded in the measurement method
field.
[0066] The positional information notification 301 transmitted from
each of the terminal apparatuses MS1 to MS5 is received by the base
station BS1. The base station BS1 transfers the positional
information notification 301 to the EM 40, and the EM 40 transfers
the positional information notification 301 to the positional
information server 80 by referring to the header. The positional
information update unit 86 of the positional information server 80
updates the positional information database 84 as illustrated in
FIG. 4 on the basis of the positional information notification
received from the terminal apparatuses MS1 to MS5. In addition, a
notification of positional information and update of the positional
information database 84 are assumed to be periodically
performed.
[0067] (2) It is assumed that the terminal apparatus MS1 crosses
the coverage hole 1a and thus communication with the base station
BS1 is suspended. If communication with the base station BS1 is
restarted, the terminal apparatus MS1 transmits an RLF notification
302 to the MDT management server 50. An example of a format of the
RLF notification 302 is illustrated in FIG. 7. The RLF notification
302 includes a header, a message type field, a positional
information field, a time stamp, a base station ID field, and a
reception level field. The MDT management server 50 is recorded as
a destination in the header. Hereinafter, it is assumed that a
value of the type field is 1 in the RLF notification 302. The RLF
generation unit 14 of the terminal apparatus MS1 records latitude,
longitude, and a height from the earth's surface indicating a
position where communication with the base station BS1 is
suspended, in the positional information field. The time stamp is
set to the time when the communication with the base station BS1 is
suspended. In addition, the RLF generation unit 14 records the
identifier BS1 for identifying the base station 20 whose
communication is suspended and a reception level of radio waves
received from the base station BS1 in the RLF notification.
[0068] The RLF notification 302 transmitted from the terminal
apparatus MS1 is received by the base station BS1. The base station
BS1 transfers the RLF notification 302 to the EM 40, and the EM 40
transfers the RLF notification 302 to the MDT management server 50
by referring to the header.
[0069] (3) The hole control unit 60 of the MDT management server 50
receives the RLF notification. The RLF processing unit 61 specifies
a position where communication is suspended from the RLF
information received from the terminal apparatus MS1, and updates
the hole information database 54. For example, it is assumed that
the following information is recorded in the hole information
database 54 as illustrated in No. 1 of FIG. 3.
[0070] A position of the coverage hole 1a: north latitude XX, east
longitude YY, and height ZZ
[0071] Base station: BS1
[0072] Reduction possibility: Yes
[0073] (4) The parameter changing unit 62 calculates a parameter
for reducing the coverage hole 1a registered in the hole
information database 54. For example, the parameter changing unit
62 calculates a tilt angle of the antenna 29 of the base station
BS1. The parameter changing unit 62 further generates a message for
notifying the calculated tilt angle, and transmits the message to
the base station BS1 via the transmission unit 51. The hole
determination unit 63 stores the number of times of transmission of
the message including the update parameter as 1 in correlation with
the coverage hole 1a. For example, the number of times of
transmission of an update parameter is stored in correlation with a
value which can uniquely specify the coverage hole 1a, such as the
numbers (No. 1) of the hole information database 54.
[0074] (5) The parameter acquisition unit 24 of the base station
BS1 acquires the parameter included in the message which is
received from the MDT management server 50. Here, a notification of
a tilt angle of the antenna 29 is sent. The parameter acquisition
unit 24 outputs the acquired tilt angle to the tilt angle
adjustment unit 25. The tilt angle adjustment unit 25 sets the
antenna 29 to the tilt angle which is input from the parameter
acquisition unit 24. The coverage hole 1a is assumed to be reduced
due to the process performed by the tilt angle adjustment unit 25
as illustrated in a state 202.
[0075] (6) Next, it is assumed that as illustrated in the state
202, the terminal apparatus MS2 passes through the coverage hole
1a, and thus communication between the terminal apparatus MS2 and
the base station BS1 is suspended. If communication with the base
station BS1 is restarted, the terminal apparatus MS2 transmits the
RLF notification 302 to the MDT management server 50. At this time,
the terminal apparatus MS2 notifies of a position of the coverage
hole 1a by using the RLF notification 30.
[0076] (7) When the RLF notification is received, the hole control
unit 60 extracts information from the RLF notification and updates
the hole information database 54 as appropriate in the same manner
as in the procedure (3). Here, the position of the coverage hole 1a
and the base station have already been registered, and thus the
hole information database 54 is not changed.
[0077] (8) The hole determination unit 63 checks whether or not the
number of times of transmission of an update parameter in relation
to the coverage hole 1a at the same position as that of the
coverage hole 1a which is desired to be reduced reaches a
predefined number of times (a threshold value of the number of
times of change). Here, the threshold value of the number of times
of change is assumed to be 2. The changing parameter for reducing
the coverage hole 1a has been sent only once, and thus the number
of times the changing parameter has been sent does not reach the
threshold value of the number of times of change. Therefore, the
parameter changing unit 62 obtains a changing parameter and
notifies the base station BS1 of the obtained parameter in the same
manner as in the procedure (4). The hole determination unit stores
the second update parameter which has been transmitted in relation
to the coverage hole 1a.
[0078] (9) The base station BS1 adjusts a tilt angle in the same
manner as in the procedure (5). Here, it is assumed that a size of
the coverage hole 1a is not changed due to the process performed by
the tilt angle adjustment unit 25.
[0079] (10) As illustrated in a state 203, the terminal apparatus
MS3 passes through the coverage hole 1a, and thus communication
between the terminal apparatus MS3 and the base station BS1 is
suspended. The terminal apparatus MS3 transmits the RLF
notification 302 to the MDT management server 50 in the same manner
as in the procedure (6).
[0080] (11) When the RLF notification is received, the hole control
unit 60 extracts information from the RLF notification in the same
manner as in the procedure (7), and confirms that the position of
the coverage hole 1a and the base station have already been
registered.
[0081] (12) The hole determination unit 63 compares the number of
times an update parameter has been transmitted in relation to the
coverage hole 1a notified of by the RLF notification, with the
threshold value of the number of times of change. At this time, the
number of times the changing parameter has been transmitted reaches
the threshold value of number of times of change. Therefore, the
hole determination unit 63 determines that the coverage hole 1a
cannot be reduced, and sets a reduction possibility of the coverage
hole 1a to "No". In other words, the hole information database 54
changes the record of the coverage hole 1a as follows.
[0082] A position of the coverage hole 1a: north latitude XX, east
longitude YY, and height ZZ
[0083] Base station: BS1
[0084] Reduction possibility: No
[0085] If the reduction possibility is set to "No", the parameter
changing unit 62 does not calculate a changing parameter. FIG. 8 is
a sequence diagram illustrating an example of a process performed
after it is determined that the coverage hole 1 cannot be improved.
The number in the parenthesis included in FIG. 8 indicates a
procedure number.
[0086] (13) If the reduction possibility is set to "No" in relation
to the coverage hole 1a, the terminal determination unit 71
transmits a terminal retrieval request to the positional
information server 80, so as to inquire about a terminal apparatus
whose distance from the coverage hole 1a is equal to or smaller
than the observation area threshold value (L). In addition, in this
example, the terminal determination unit 71 and the message
generation unit 72 are assumed to store the observation area
threshold value (L) and the warning area threshold value (X) in
advance.
[0087] An example of a message format of the terminal retrieval
request is illustrated in 303 of FIG. 7. The terminal retrieval
request includes a header, a message type field, a hole position
field, an observation area threshold value field, and an inquiry
number field. It is assumed that the message type field is set to 2
in the terminal retrieval request. The terminal determination unit
71 sets a value of the hole position field to positional
information of the coverage hole 1a, and sets a value of the
observation area threshold value field to the observation area
threshold value (L). In addition, an inquiry number is recorded in
the inquiry number field, the inquiry number being determined so as
to uniquely recognize the coverage hole 1a around which the
terminal apparatus 10 is located, about which an inquiry is made.
The terminal determination unit 71 transmits the terminal retrieval
request to the positional information server 80.
[0088] (14) The terminal retrieval unit 85 of the positional
information server 80 retrieves the terminal apparatus 10 whose
distance from a position of the coverage hole 1 designated in the
terminal retrieval request is equal to or smaller than the
observation area threshold value. The terminal retrieval unit 85 is
assumed to refer to the positional information database 84 in order
to retrieve the terminal apparatus 10. Here, it is assumed that
four terminal apparatuses 10 including MS1, MS2, MS3, and MS4 are
located at a distance which is equal to or smaller than the
observation area threshold value (L) from the coverage hole 1.
[0089] (15) The terminal retrieval unit 85 transmits a retrieval
result message to the MDT management server 50 in order to send a
notification of the obtained terminal apparatuses 10. An example of
a format of the retrieval result message is illustrated in 304 of
FIG. 7. The retrieval result message includes a header, a message
type field, a corresponding number field, a terminal ID field, and
an inquiry number field. It is assumed that the message type field
is set to 3 in the retrieval result message. The terminal retrieval
unit 85 sets a value of the inquiry number field to the value which
has been stored in the inquiry number field of the terminal
retrieval request received in the procedure (14). In addition, the
number of terminal apparatuses 10 located at a distance within L
from the coverage hole 1a is recorded in the corresponding number
field, and an identifier for identifying each of the terminal
apparatuses 10 located at a distance within L from the coverage
hole 1a is recorded in the terminal ID field. Here, it is assumed
that is recorded in the corresponding number field, and identifiers
including MS1, MS2, MS3, and MS4 are recorded in the terminal ID
field.
[0090] (16) The terminal determination unit 71 extracts information
included in the retrieval result message which is transmitted from
the positional information server 80, and outputs the obtained IDs
of the terminal apparatuses to the message generation unit 72. At
this time, it is assumed that the terminal determination unit 71
also notifies the message generation unit 72 of the coverage hole 1
correlated with the inquiry number.
[0091] (17) The message generation unit 72 generates a hole
notification when the terminal IDs are input from the terminal
determination unit 71. An example of the hole notification is
illustrated in 305 of FIG. 7. The hole notification includes a
header, a message type field, an MME identifier field, a base
station ID field, a terminal ID field, a hole position field, an
observation area threshold value field, and a warning area
threshold value field. It is assumed that the message type field is
set to 4 in the hole notification. The message generation unit 72
records an ID of abase station with which the terminal apparatus 10
as a notification destination currently communicates in the base
station ID field, and records an identifier of the terminal
apparatus 10 as a notification destination in the terminal ID
field. A position of the coverage hole 1 is recorded in the hole
position field. L(m) which is the observation area threshold value
is recorded in the observation area threshold value field, and X(m)
which is the warning area threshold value is recorded in the
warning area threshold value field.
[0092] An identifier of the MME 30 connected to the base station 20
with which the terminal apparatus 10 as a notification destination
currently communicates is recorded in the MME identifier field. The
message generation unit 72 inquires the EM 40 about identification
information of the MME 30 connected to the base station 20 with
which the terminal apparatus 10 as a notification destination
currently communicates. The message generation unit 72 records the
information whose notification has been sent from the EM 40, in the
MME identifier field. When the hole notification 305 is generated,
the message generation unit 72 transmits the message to the
terminal apparatuses MS1 to MS4 which are destinations.
[0093] (18) The terminal apparatuses MS1 to MS4 receive the hole
notification 305. The position detection unit 17 of the terminal
which has received the hole notification 305 increases a frequency
of detecting a position. For example, the position detection unit
17 may acquire positional information in real time. The calculation
unit 15 calculates a distance from the coverage hole 1 which has
been notified of by the hole notification each time the present
position is detected by the position detection unit 17. The warning
unit 16 performs a process for attracting a user's attention when a
distance calculated by the calculation unit 15 is equal to or
smaller than X m. For example, the warning unit 16 displays
information for warning of coming close to the coverage hole 1, on
the display 101. In the example of the state 203 illustrated in
FIG. 6, distances of MS1, MS3, and MS4 from the coverage hole 1 is
equal to or smaller than the warning area threshold value (X).
Therefore, in MS1, MS3, and MS4, warnings are issued to users
thereof.
[0094] In addition, a single terminal apparatus 10 may receive a
hole notification in relation to a plurality of coverage holes 1.
FIG. 9 illustrates examples of a calculation result in the
calculation unit 15 and a determination result of whether or not a
warning is issued. It is assumed that FIG. 9 illustrates a
calculation example in the terminal apparatus MS4, and the terminal
apparatus MS4 receives hole notifications of two coverage holes 1
including a coverage hole 1a and a coverage hole 1b. The
calculation unit 15 of the terminal apparatus MS4 stores positions
of the coverage holes 1 included in the hole notifications. Here,
it is assumed that No. 1 of FIG. 9 is data of the coverage hole 1a,
and No. 2 is data of the coverage hole 1b. When the position
detection unit 17 notifies the calculation unit 15 that the present
position of the terminal apparatus MS4 is indicated by north
latitude A, east longitude B, and a height C, the calculation unit
15 calculates distances from the coverage holes 1a and 1b whose
notification has already been sent. An operation used to calculate
a distance may employ any operation method for obtaining a distance
between two points of which latitude, longitude, and a height are
known. Here, it is assumed that a distance from the present
location of the terminal apparatus MS4 to the coverage hole 1a is
D1, and a distance from the present location of the terminal
apparatus MS4 to the coverage hole 1b is D2. Here, it is assumed
that a magnitude of the observation area threshold value L and the
warning area threshold value X is L>D2>X>D1. Then, since
D1 is equal to or smaller than X, the warning unit 16 displays a
screen for warning that the terminal apparatus MS4 approaches the
coverage hole 1a on the display 101. On the other hand, in relation
to the coverage hole 1b, the distance from the terminal apparatus
MS4 is smaller than the observation area threshold value, but is
larger than the warning area threshold value, and thus a warning is
not given. However, a distance between the coverage hole 1b and the
terminal apparatus MS4 continues to be observed.
[0095] FIG. 10 is a flowchart illustrating an example of an
operation of the terminal apparatus 10 which receives a hole
notification. FIG. 10 illustrates an example of the operation
performed in the procedure (18). If the terminal apparatus 10
receives a hole notification, the calculation unit 15 acquires
positional information of the coverage hole 1, the observation area
threshold value L, and the warning area threshold value X (step
S1). The position detection unit 17 increases a frequency of
acquiring positional information, and acquires positional
information in real time (steps S2 and S3). The calculation unit 15
obtains a distance between the terminal apparatus 10 and the
coverage hole 1, and the warning unit 16 compares the distance with
the warning area threshold value X (step S4). If the distance
between the terminal apparatus 10 and the coverage hole 1 is equal
to or smaller than the warning area threshold value X, the warning
unit 16 displays a warning on the display 101 in order to attract
user's attention (Yes in step S4, and step S5). Then, the processes
in step S3 and subsequent steps are repeatedly performed.
[0096] On the other hand, if the distance between the terminal
apparatus 10 and the coverage hole 1 is larger than the warning
area threshold value X, the warning unit 16 compares the distance
between the terminal apparatus 10 and the coverage hole 1 with the
observation area threshold value L (No in step S4, and step S6). If
the distance between the terminal apparatus 10 and the coverage
hole 1 is smaller than the observation area threshold value L, the
processes in step S3 and subsequent steps are repeatedly performed
(No in step S6). If the distance between the terminal apparatus 10
and the coverage hole 1 is equal to or larger than the observation
area threshold value L, a possibility of approaching the coverage
hole 1 is reduced, and thus monitoring a distance to the coverage
hole 1 is finished. Therefore, the position detection unit 17
decreases a frequency of acquiring positional information (step
S7). In addition, the calculation unit 15 erases data on the
coverage hole 1 whose distance from the terminal apparatus 10 is
larger than the observation area threshold value (step S8).
[0097] As mentioned above, when the terminal apparatus 10 comes
close to the coverage hole 1 which is determined as being incapable
of being improved, a warning is given to a user of the terminal
apparatus 10, and the user can easily avoid the coverage hole so
that communication is performed.
Second Embodiment
[0098] In a second embodiment, a description will be made of a case
where a base station 90 specifies the terminal apparatus 10 which
is a notification target of a position of the coverage hole 1.
[0099] [Apparatus Configuration]
[0100] FIG. 11 is a diagram illustrating configuration examples of
apparatuses which operate in the second embodiment. Configurations
or operations of the terminal apparatus 10, the MME 30, and the EM
40 are the same as in the first embodiment.
[0101] Abase station 90 includes not only the wireless unit 23, the
parameter acquisition unit 24, the tilt angle adjustment unit 25,
and the interface 28, but also a hole notification processing unit
91, a terminal determination unit 92, a message generation unit 93,
and a terminal database 94. When a message for notifying a position
of the coverage hole 1 which cannot be improved is received from an
MDT management server 55, the hole notification processing unit 91
extracts the position of the coverage hole 1. The terminal
determination unit 92 specifies a terminal which is a notification
target of information on the coverage hole 1. At this time, the
terminal determination unit 92 may refer to the terminal database
94 as appropriate. The terminal database 94 stores an identifier of
a terminal which currently performs communication with the base
station 90. The message generation unit 93 generates a message
which will be transmitted to the terminal specified by the terminal
determination unit 92. A format of the message generated by the
message generation unit 93 or a message transmission method will be
described later. Operations of the wireless unit 23, the parameter
acquisition unit 24, the tilt angle adjustment unit 25, and the
interface 28 are the same as in the base station 20.
[0102] In the present embodiment, the MDT management server 55 is
used instead of the MDT management server 50. The MDT management
server 55 includes not only a hole notification unit 64 but also
the interface 53, the hole information database 54, and the hole
control unit 60. The hole notification unit 64 notifies the base
station 90 of a position of the coverage hole 1 which is determined
as being incapable of being improved by the hole determination unit
63. In addition, the hole notification unit 64 is assumed to store
an observation area threshold value and a warning area threshold
value in advance. Operations of the interface 53, the hole
information database 54, and the hole control unit 60 are the same
as in the first embodiment.
[0103] [Communication Method]
[0104] FIG. 12 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole 1a
cannot be reduced in the second embodiment. The number in the
parenthesis included in FIG. 12 indicates a procedure number.
Operations performed from starting of communication in a terminal
to detection of the coverage hole 1 which cannot be improved are
the same as the procedures (1) to (12) described in the first
embodiment.
[0105] (21) If a reduction possibility of the coverage hole 1a is
set to "No", the hole notification unit 64 generates a hole
notification 306 which will be transmitted to the base station 90.
FIG. 13 illustrates an example of a format of the hole notification
306. The hole notification 306 includes a header, a message type
field, a base station ID field, a hole position field, an
observation area threshold value field, and a warning area
threshold value field. It is assumed that the message type field is
set to 5 in the hole notification 306. The hole notification unit
64 records an identifier of abase station whose communication area
includes the coverage hole 1a or an identifier of a base station
whose communication area is adjacent to the coverage hole 1a, in
the base station ID field. In addition, an address of the base
station whose identifier is recorded in the base station ID field
is set in the header. Values recorded in the hole position field,
the observation area threshold value field, and the warning area
threshold value field are the same as those of the hole
notification 305. In the following description, a base station BS1
is notified of a position of the coverage hole la.
[0106] (22) When the hole notification 305 is received, the hole
notification processing unit 91 of the base station 90 acquires
positional information of the coverage hole 1a from the value of
the hole position field. The hole notification processing unit 91
outputs the positional information of the coverage hole 1a to the
message generation unit 93. The terminal determination unit 92
specifies a terminal apparatus which currently communicates with
the base station 90 by referring to the terminal database 94. In
addition, the terminal determination unit 92 also specifies the
terminal apparatus 10 which is being handed over (HO) to the base
station 90. Further, the terminal determination unit 92 also
specifies the terminal apparatus 10 which is being connected to the
base station 90 because of being newly powered on or the like
within a communication area of the base station 90. The terminal
determination unit 92 outputs an identifier of the specified
terminal apparatus 10 to the message generation unit 93, coupling
the identifier with a state of the terminal apparatus 10.
[0107] (23) The message generation unit 93 transmits a hole
information notification to the terminal apparatus 10 of which
communication is in progress, among the terminal apparatuses 10
which have been notified of by the terminal determination unit 92.
The hole information notification includes not only a header but
also a terminal ID field, a hole position field, an observation
area threshold value field, and a warning area threshold value
field. An identifier of the destination terminal apparatus 10 is
recorded in the terminal ID field, and a position of the coverage
hole 1 is recorded in the hole position field. In addition,
information on the observation area threshold value L is recorded
in the observation area threshold value field, and information on
the warning area threshold value X is recorded in the warning area
threshold value field. The message generation unit 93 transmits the
generated message to the destination terminal apparatus 10 via the
wireless transmission unit 21.
[0108] (24) The message generation unit 93 generates a message
(handover response message) which will be transmitted to the
terminal apparatus 10 which is being handed over to the base
station 90, among the terminal apparatuses 10 which have been
notified of by the terminal determination unit 92. The handover
response message includes information on the coverage hole 1a. An
example of the handover response message 307 is illustrated in FIG.
13. The handover response message is transmitted through signaling
between the base station 90 and the terminal apparatus 10. The
handover response message includes a handover response field, a
handover control information field, and a hole notification field.
Information indicating that a message is a handover response is
recorded in the handover response field. Information which is used
to hand over the terminal apparatus 10 is recorded in the handover
control information field. In addition, a terminal ID, a position
of the coverage hole 1, the observation area threshold value, and
the warning area threshold value are recorded in the hole
notification field. An example of the hole notification field is
illustrated in 308 of FIG. 13. Further, the observation area
threshold value is recorded in an observation area field, and the
warning area threshold value is recorded in a warning area
field.
[0109] (25) The message generation unit 93 generates a message
(initial connection response message) which will be transmitted to
the terminal apparatus 10 which is being connected to the base
station 90, among the terminal apparatuses 10 which have been
notified of by the terminal determination unit 92. The initial
connection response message includes information on the coverage
hole 1a. An example of the initial connection response message 309
is illustrated in FIG. 13. The initial connection response message
is also transmitted through signaling between the base station 90
and the terminal apparatus 10. The initial connection response
message includes an initial connection response field, an initial
connection control information field, and a hole notification
field. Information indicating that a message is an initial
connection response is recorded in the initial connection response
field. Information used to initially connect the terminal apparatus
10 to the base station 90 is recorded in the initial connection
control information field. The hole notification field is the same
as the hole notification field 308 of the handover response.
[0110] (26) The terminal apparatus 10 in an observation area of the
base station 90 receives any one of the messages transmitted in the
procedures (23) to (25). The position detection unit 17 of the
terminal apparatus 10 which has received a notification of the
position of the coverage hole 1a increases a frequency of detecting
a position. In addition, the calculation unit 15 calculates a
distance from the coverage hole 1 whose notification has been sent
by using the hole notification, each time the present position is
detected by the position detection unit 17. The warning unit 16
displays information for warning of being close to the coverage
hole 1 on the display 101 when a distance calculated by the
calculation unit 15 is equal to or smaller than X m.
[0111] FIG. 14 is a flowchart illustrating an example of a process
performed by the base station 90 when a notification of a position
of the coverage hole 1 is sent. When the base station 90 receives
the hole notification 306 from the MDT management server 50, the
hole notification processing unit 91 extracts positional
information of the coverage hole 1, the observation area threshold
value L, and the warning area threshold value X from the hole
notification 306 (step S11). The hole notification processing unit
91 outputs the extracted information to the terminal determination
unit 92. The terminal determination unit 92 extracts all the
terminal apparatuses 10 which are currently in communication with
the base station 90, and notifies the message generation unit 93 of
the extracted terminal apparatuses (step S12). The message
generation unit 93 transmits a hole notification to all the
extracted terminals (step S13).
[0112] Next, the terminal determination unit 92 checks whether or
not there is the terminal apparatus 10 which enters the
communication area of the base station 90 through handover (step
S14). If the terminal apparatus 10 which enters the communication
area of the base station 90 through handover can be specified, the
terminal determination unit 92 notifies the message generation unit
93 of the specified terminal apparatus 10 (Yes in step S14). The
message generation unit 93 transmits the handover response message
307 (refer to FIG. 13) to the terminal apparatus 10 which has been
notified of by the terminal determination unit 92 (step S15).
[0113] In addition, the terminal determination unit 92 checks
whether or not there is the terminal apparatus 10 which is starting
new connection to the base station 90 (step S16). If the terminal
apparatus 10 which is starting new connection to the base station
90 can be specified, the terminal determination unit 92 notifies
the message generation unit 93 of the specified terminal apparatus
10 (Yes in step S16). The message generation unit 93 transmits a
new connection response message 309 (refer to FIG. 13) to the
terminal apparatus 10 which has been notified of by the terminal
determination unit 92, so as to send information on the coverage
hole 1 (step S17). Then, the processes in step S13 and the
subsequent steps are repeatedly performed.
[0114] In addition, FIG. 14 illustrates one process example, and
there can be a case where an order of the processes is changed in
accordance with implementations, such as, for example, the
processes in steps S16 and S17 can be performed before the
processes in steps S14 and S15.
[0115] FIG. 15 is a flowchart illustrating an example of an
operation of the terminal apparatus 10 which is notified of a
position of the coverage hole 1. The calculation unit 15 of the
terminal apparatus 10 acquires positional information of the
coverage hole 1, the observation area threshold value L, and the
warning area threshold value X from information received from the
base station 90 (step S21). Processes in steps S22 to S27 are the
same as the processes in steps S2 to S7 described with reference to
FIG. 10. After the position detection unit 17 decreases a frequency
of acquiring positional information in step S27, the calculation
unit 15 checks whether or not communication between the terminal
apparatus 10 and the base station 90 which is currently connected
thereto is finished (step S28). If communication with the currently
connected base station 90 is finished, the calculation unit 15
erases the positional information of the coverage hole 1, the
observation area threshold value L, and the warning area threshold
value X (Yes in step S28, and step S29). On the other hand, if
communication with the currently connected base station 90 is not
finished, the processes in step S23 and the subsequent steps are
repeatedly performed (No in step S28).
Third Embodiment
[0116] In a third embodiment, a description will be made of a case
where the terminal apparatus 10 which is a notification target of a
position of the coverage hole 1 is specified by the MME 30.
[0117] [Apparatus Configuration]
[0118] FIG. 16 is a diagram illustrating configuration examples of
apparatuses which operate in the third embodiment. Configurations
or operations of the base station 20 and the EM 40 are the same as
in the first embodiment. A configuration of the terminal apparatus
10 is the same as in the first embodiment, but, in the third
embodiment, the terminal apparatus 10 is assumed to notify the MME
30 of positional information. In the present embodiment, the MDT
management server 55 is included in a network.
[0119] A configuration and an operation of the MDT management
server 55 are the same as in the second embodiment. However, the
hole notification unit 64 is assumed to notify the MME 30 of a
position of the coverage hole 1 which is determined as being
incapable of being improved by the hole determination unit 63. FIG.
17 illustrates an example of a message format of a hole
notification 311. The hole notification unit 64 of the MDT
management server 55 specifies the base station 20 whose
communication area includes the coverage hole 1 or the base station
20 whose communication area is adjacent to the coverage hole 1 when
the hole notification 311 is generated. In addition, the hole
notification unit 64 inquires the EM 40 about the MME 30 which is
connected to the specified base station 20. The hole notification
unit 64 sets the MME 30 whose notification has been sent from the
EM 40 as a destination of the hole notification 311, and records an
identifier thereof in an MME identifier field of the hole
notification 311. Values recorded in a hole position field, an
observation area field, and a warning area field are the same as
those of the hole notification 205.
[0120] The MME 30 used in the present embodiment includes an
interface 33, a terminal management unit 34, a terminal information
database 35, a hole notification processing unit 37, and a message
generation unit 38. The interface 33 is provided with a
transmission unit 31 and a reception unit 32, and performs
communication with the base station 20, the EM 40, and the MDT
management server 55. The terminal management unit 34 includes a
terminal-in-area management unit 341, a tracking area update (TAU)
processing unit 342, and an initial attachment processing unit 343.
The terminal-in-area management unit 341 processes information on
the terminal apparatus 10 which is located in a tracking area
managed by the MME 30 and whose connection with the MME 30 is
established. The TAU processing unit 342 processes a message which
is transmitted and received when tracking area update (TAU) is
performed. Here, the tracking area update indicates that the
terminal apparatus 10 moves to a tracking area managed by the MME
30 from another tracking area. The initial attachment processing
unit 343 processes a message which is transmitted and received for
initial attachment. The initial attachment is a process in which
the terminal apparatus 10 is connected to the MME 30 when the
terminal apparatus 10 is powered on within the tracking area
managed by the MME 30. The terminal-in-area management unit 341,
the TAU processing unit 342, and the initial attachment processing
unit 343 all update the terminal information database 35 when a
connection relationship between the terminal apparatus 10 and the
MME 30 is updated by transmission and reception of a message. The
terminal information database 35 stores an identifier of the
terminal apparatus 10 and a position of the terminal apparatus 10
in correlation with each other.
[0121] The hole notification processing unit 37 processes the hole
notification 311 received from the MDT management server 55 so as
to acquire a position of the coverage hole 1, the observation area
threshold value, and the warning area threshold value. The hole
notification processing unit 37 outputs the acquired information to
the message generation unit 38. The message generation unit 38
specifies the terminal apparatus 10 connected to the MME 30 by
referring to the terminal information database 35. In addition, the
message generation unit 38 generates a notification message 312
which will be transmitted to the specified terminal apparatus 10.
An example of a format of the notification message 312 is
illustrated in FIG. 17. In a header of the notification message
312, an address of the MME 30 is set as a transmission source
address, and an address of the terminal apparatus 10 which is a
destination is set as a destination address. In addition, the
header includes a message type field, and a value (6 in the example
of FIG. 17) correlated with the notification message 312 is
recorded in the message type field. Further, the notification
message 312 includes a position of the coverage hole 1, the
observation area threshold value, and the warning area threshold
value.
[0122] In addition, the interface 33 is realized by the interface
123 (FIG. 5). In addition, the CPU 121 reads a program recorded on
the HDD 122 and thus operates as the terminal management unit 34,
the terminal information database 35, the hole notification
processing unit 37, and the message generation unit 38.
[0123] [Communication Method]
[0124] FIG. 18 is a sequence diagram illustrating an example of a
process performed after it is determined that the coverage hole 1a
cannot be reduced in the third embodiment. Operations performed
from starting of communication in a terminal to detection of the
coverage hole 1 which cannot be improved are the same as the
procedures (1) to (12) described in the first embodiment.
[0125] (31) If a reduction possibility of the coverage hole la is
set to "No", the hole notification unit 64 generates a hole
notification 311 which will be transmitted to the MME 30.
[0126] (32) When the hole notification 311 is received, the hole
notification processing unit 37 of the MME 30 acquires positional
information of the coverage hole 1a from the value of the hole
position field. The hole notification processing unit 37 outputs
the positional information of the coverage hole 1a to the message
generation unit 38. The message generation unit 38 specifies a
terminal apparatus 10 which is currently connected to the MME 30 by
referring to the terminal information database 35. In addition, the
message generation unit 38 inquires the TAU processing unit 342
about information on the terminal apparatus 10 which is updating a
tracking area of the MME 30. Further, the message generation unit
38 inquires the initial attachment processing unit 343 about the
terminal apparatus 10 which has requested initial attachment.
[0127] (33) The message generation unit 38 transmits the
notification message 312 to the terminal apparatus 10 recorded in
the terminal information database 35. In addition, the message
generation unit 38 also transmits the notification message 312 to
the terminal apparatuses 10 which have been notified of by the TAU
processing unit 342 and the initial attachment processing unit
343.
[0128] (34) In the terminal apparatus 10 which has received the
notification message 312, the position detection unit 17 increases
a frequency of detecting a position of the terminal apparatus 10.
The calculation unit 15 calculates a distance from the position of
the coverage hole 1 included in the notification message 312 to the
present location on the basis of information obtained from the
position detection unit 17. Next, the warning unit 16 compares the
calculation result from the calculation unit 15 with the warning
area threshold value X. If the distance from the coverage hole 1 to
the present location is equal to or smaller than the warning area
threshold value X, the warning unit 16 displays information for
informing of coming close to the coverage hole 1, on the display
101. If the distance from the coverage hole 1 to the present
location is larger than the warning area threshold value X, the
warning unit 16 compares the distance from the coverage hole 1 to
the present location with the observation area threshold value L.
If the distance from the coverage hole 1 to the present location is
larger than the observation area threshold value L, the position
detection unit 17 decreases a frequency of acquiring positional
information. In addition, in a case where communication is not
performed, the terminal apparatus 10 may perform so as not to
acquire positional information in real time or not to issue a
warning. In this case, a processing burden on a terminal which does
not perform communication is reduced.
[0129] FIG. 19 is a flowchart illustrating an example of a process
performed by the MME 30 when a notification of a position of the
coverage hole 1 is received. FIG. 19 illustrates an example of the
process in the procedure (32) of FIG. 18. In addition, FIG. 19
illustrates one process example, and there can be a case where an
order of processes is changed in accordance with implementations,
such as, for example, processes insteps S46 and S47 can be
performed before processes in steps S44 and S45.
[0130] When the MME 30 receives the hole notification 311 from the
MDT management server 50, the hole notification processing unit 37
extracts positional information of the coverage hole 1, the
observation area threshold value L, and the warning area threshold
value X from the hole notification 311 (step S41). The hole
notification processing unit 37 outputs the extracted information
to the message generation unit 38. The message generation unit 38
acquires information on the terminal apparatus 10 which is
currently connected to the MME 30 from the terminal information
database 35, and transmits the notification message 312 to the
obtained terminal apparatus 10 (steps S42 and S43).
[0131] Next, the message generation unit 38 inquires the TAU
processing unit 342 about whether or not there is the terminal
apparatus 10 which enters a corresponding area of the MME 30
through tracking area update (step S44). If the terminal apparatus
10 which enters the corresponding area of the MME 30 can be
specified, the message generation unit 38 transmits the
notification message 312 to the specified terminal apparatus 10 to
notify of information on the coverage hole 1 (Yes in step S44, and
step S45).
[0132] In addition, the message generation unit 38 inquires the
initial attachment processing unit 343 about whether or not there
is the terminal apparatus 10 which is starting new connection to
the MME 30 (step S46). If the terminal apparatus 10 which is
starting new connection to the MME 30 can be specified, the message
generation unit 38 transmits the notification message 312 to the
specified terminal apparatus 10 to notify of information on the
coverage hole 1 (Yes in step S46, and step S47). The processes in
step S44 and the subsequent steps are repeatedly performed in both
a case where a determination result in step S46 is negative (No)
and a case where the process in step S47 is completed.
[0133] FIGS. 20A and 20B are flowcharts illustrating an example of
an operation of a terminal apparatus 10 which has been notified of
a position of a coverage hole 1. FIGS. 20A and 20B illustrate an
example of the process in the procedure (34) of FIG. 18. The
calculation unit 15 of the terminal apparatus 10 acquires
positional information of the coverage hole 1, the observation area
threshold value L, and the warning area threshold value X from
information received from the MME 30 (step S51). In a case where
the terminal apparatus 10 is not performing communication, the
calculation unit 15 checks whether or not the terminal apparatus
has moved from a corresponding area of the present MME 30 to a
corresponding area of another MME 30 (No in step S52, and step
S53). If the terminal apparatus has moved to the corresponding area
of another MME 30, the calculation unit 15 deletes information on
the coverage hole 1 which is currently stored (Yes in step S53, and
step S54). If the terminal apparatus has not moved to the
corresponding area of another MME 30, the processes in step S52 and
the subsequent steps are repeatedly performed (No in step S53).
[0134] On the other hand, in a case where the terminal apparatus 10
currently is performing communication, the position detection unit
17 starts acquiring positional information in real time (Yes in
step S52, and step S55). Processes in steps S56 to S60 are the same
as the processes in steps S3 to S7 described with reference to FIG.
10. After the position detection unit 17 decreases a frequency of
acquiring positional information in step S60, the calculation unit
15 checks whether or not communication of the terminal apparatus 10
is finished (step S61). In a case where communication of the
terminal apparatus 10 is finished, the processes in step S52 and
the subsequent steps are repeatedly performed (Yes in step
S61).
[0135] In a case where communication of the terminal apparatus 10
is not finished, the calculation unit 15 calculates again a
distance from the coverage hole 1 by using the latest positional
information obtained from the position detection unit 17, and then
compares an obtained value with the observation area threshold
value L (No in step S61, and steps S62 and S63). If the distance
between the terminal apparatus 10 and the coverage hole 1 is within
the observation area threshold value L, the processes in step S55
and the subsequent steps are repeatedly performed (Yes in step
S63). If the distance between the terminal apparatus 10 and the
coverage hole 1 exceeds the observation area threshold value L, the
calculation unit 15 checks whether or not the terminal apparatus
has moved from the corresponding area of the present MME 30 to a
corresponding area of another MME 30 (No in step S63, and step
S64). In a case where the terminal apparatus has moved to the
corresponding area of another MME 30, the calculation unit 15
deletes information on the coverage hole 1 which is currently
stored (Yes in step S64, and step S65). If the terminal apparatus
has not moved to the corresponding area of another MME 30, the
processes in step S61 and the subsequent steps are repeatedly
performed (No in step S63).
Fourth Embodiment
[0136] FIG. 21 illustrates an example of a system according to a
fourth embodiment. In the fourth embodiment, when a coverage hole 1
which cannot be improved is detected, the MDT management server 55
notifies an application server 160 of the latest information on a
position of the coverage hole 1. The application server 160 stores
an identifier of each terminal apparatus 10 which has downloaded an
application provided by the application server 160. The application
server 160 sends a notification of a position of the coverage hole
1 to all terminal apparatuses 10 whose identifiers are stored in
the application server 160, each time information on a position of
the coverage hole 1 is updated. The terminal apparatus 10 measures
a distance between the present location and the coverage hole 1
correlated with the base station 20 in communication with the
terminal apparatus 10 among the coverage holes 1 whose
notifications have been sent. If a distance from the coverage hole
1 is equal to or smaller than the warning area threshold value, the
terminal apparatus 10 displays a message on the display 101 in
order to issue a warning to a user.
[0137] FIG. 22 illustrates a configuration example of the
application server 160. The application server 160 includes an
interface 163, a hole notification processing unit 164, a download
request processing unit 165, a message generation unit 166, and a
terminal information database 167. The interface 163 is provided
with a transmission unit 161 and a reception unit 162, and performs
communication with the base station 20, the MME 30, the EM 40, and
the MDT management server 55 as appropriate. The hole notification
processing unit 164 processes a hole notification which is received
from the MDT management server 55. A format of the hole
notification which is transmitted from the MDT management server 55
to the application server 160 is the same as the hole notification
306 illustrated in FIG. 13. The hole notification processing unit
164 acquires a position of the coverage hole 1, the observation
area threshold value (L), the warning area threshold value (X), and
an identifier of the base station 20 from the hole notification,
and stores the information. Here, it is assumed that an identifier
of the base station 20 whose communication area includes the
coverage hole 1 whose notification has been sent or an identifier
of the base station 20 whose communication area is adjacent to the
coverage hole 1 is recorded in the hole notification.
[0138] The download request processing unit 165 processes a
download request which is made from the terminal apparatus 10 to
the application server 160. At this time, the download request
processing unit 165 requests the terminal apparatus 10 which is
allowed to download an application, to send a notification of an
identifier for identifying the terminal apparatus 10. The download
request processing unit 165 acquires the identifier of the terminal
apparatus 10 from a message which is transmitted from the terminal
apparatus 10, and stores the identifier in the terminal information
database 167.
[0139] When the information on the coverage hole 1 stored in the
hole notification processing unit 164 is updated, the message
generation unit 166 generates a message for transmitting
information stored in the hole notification processing unit 164 in
correlation with the coverage hole 1 to the terminal apparatus 10.
The terminal apparatuses 10 which are transmission destination of
the message are all terminal apparatuses 10 whose identifiers are
stored in the terminal information database 167.
[0140] The application server 160 includes a CPU, an HDD, and an
interface as hardware in the same manner as the EM 40, the MDT
management server 55, or the like. The interface operates as the
transmission unit 161 and the reception unit 162. The CPU reads a
program from the HDD so as to operate as the hole notification
processing unit 164, the download request processing unit 165, the
message generation unit 166, and the terminal information database
167.
[0141] FIG. 23 is a sequence diagram illustrating an example of a
process performed after it is determined that a coverage hole
cannot be reduced in the fourth embodiment. Operations performed
from starting of communication with the terminal apparatus 10 to
detection of the coverage hole 1 which cannot be improved are the
same as the procedures (1) to (12) described in the first
embodiment.
[0142] (41) If a reduction possibility of the coverage hole la is
set to "No", the hole notification unit 64 transmits a hole
notification to the application server 160.
[0143] (42) When the hole notification is received, the hole
notification processing unit 164 of the application server 160
acquires a position of the coverage hole 1, the observation area
threshold value (L), the warning area threshold value (X), and an
identifier of the base station 20. In addition, the hole
notification processing unit 164 stores the acquired information.
The message generation unit 166 generates a message for notifying
information on all coverage holes 1 stored in the hole notification
processing unit 164. A destination of the notification message
generated here is each terminal whose identifier is recorded in the
terminal information database 167. FIG. 24 illustrates an example
of a format of the notification message generated here.
[0144] (43) The message generation unit 166 transmits the generated
notification message to the terminal apparatus 10 which is a
destination.
[0145] (44) The terminal apparatus 10 which has received the
notification message checks whether or not there is a coverage hole
1 correlated with the same identifier as an identifier of the base
station 20 which is a connection destination of the terminal
apparatus 10. Hereinafter, the coverage hole 1 which is correlated
with the same identifier as the identifier of the base station 20
which is a connection destination of the terminal apparatus 10 is
referred to as a "processing target coverage hole 1". In a case
where the processing target coverage hole 1 is detected, the
position detection unit 17 increases a frequency of detecting a
position of the terminal apparatus 10. The calculation unit 15
calculates a distance from a position of the processing target
coverage hole 1 to the present location on the basis of information
obtained from the position detection unit 17. Next, the warning
unit 16 compares a calculation result from the calculation unit 15
with the warning area threshold value X. If the distance from the
processing target coverage hole 1 to the present location is equal
to or smaller than the warning area threshold value X, the warning
unit 16 displays information for warning of coming close to the
coverage hole 1, on the display 101. If the distance from the
processing target coverage hole 1 to the present location is larger
than the warning area threshold value X, the warning unit 16
compares the distance from the coverage hole 1 to the present
location with the observation area threshold value L. If the
distance from the processing target coverage hole 1 to the present
location is larger than the observation area threshold value L, the
position detection unit 17 decreases a frequency of acquiring
positional information.
[0146] FIG. 25 is a flowchart illustrating an example of an
operation of a terminal apparatus which has been notified of a
position of a coverage hole. When a notification message is
received, the terminal apparatus 10 acquires an identifier of the
base station 20 which forms a communication area where the terminal
apparatus 10 is located (steps S71 and S72). If the identifier
acquired in step S72 matches an identifier of the base station 20
correlated with the coverage hole 1, the position detection unit 17
starts acquiring positional information in real time (Yes in step
S73, and step S74). Processes in steps S74 to S77 are the same as
the processes in steps S2 to S5 described with reference to FIG.
10. The processes in step S72 and the subsequent steps are
repeatedly performed in a case where a determination result in step
S76 is negative (No), or a case where the process in step S77 is
completed. On the other hand, if a processing target coverage hole
1 is not found in step S73, the position detection unit 17 changes
setting so that positional information is not acquired in real time
(No in step S73, and step S78).
[0147] <Others>
[0148] In addition, an embodiment is not limited to the
above-described embodiments, and may be variously modified. For
example, the above-described frame format is only an example, and
may be changed in accordance with implementations. Further, the
information elements included in a database may be changed in
accordance with implementations.
[0149] In addition, the observation area threshold value L and the
warning area threshold value X may be stored in advance in an
individual apparatus such as the terminal apparatus 10, the base
station 90, and the MME 30. In this case, the observation area
threshold value L or the warning area threshold value X is not
transmitted and received between the apparatuses.
[0150] There is a case where the RLF processing unit 61 is modified
so as to determine that the coverage hole 1 is detected when the
number of times of receiving RLF notifications as to locations
included in a specific range from a certain location exceeds a
predetermined value which is stored in advance.
[0151] Further, the methods according to the embodiments may also
be applied to systems employing communication methods other than
LTE.
[0152] Therefore, by applying the embodiments, a user can easily
avoid a coverage hole on the basis of hole information received by
a terminal so that communication can be performed.
[0153] All examples and conditional language provided herein are
intended for the pedagogical purposes of aiding the reader in
understanding the invention and the concepts contributed by the
inventor to further the art, and are not to be construed as
limitations to such specifically recited examples and conditions,
nor does the organization of such examples in the specification
relate to a showing of the superiority and inferiority of the
invention. Although one or more embodiments of the present
invention have been described in detail, it should be understood
that the various changes, substitutions, and alterations could be
made hereto without departing from the spirit and scope of the
invention.
* * * * *